1. Field of the Invention
The present invention relates to a mobile terminal, and a method for improving radiation performance and a Specific Absorption Rate (SAR) of an antenna of a mobile terminal. More particularly, the present invention relates to a portable terminal having increased radiation performance and a SAR according to various frequency bands supported by a mobile terminal, and a method for improving radiation performance and a SAR of an antenna.
2. Description of the Related Art
Recently, as mobile terminals become smaller while supporting increased bandwidth, larger frequency ranges are being covered by small antennas of the mobile terminals. As such, in order to improve a Total Radiated Power (TRP), a Total Isotropic Sensitivity (TIS) and the Specific Absorption Rate (SAR) according to the bandwidth or frequency range of one antenna, methods of changing the antenna pattern and antenna matching have been used. However, as an antenna gets smaller, it has become difficult to change a structure or pattern for such an antenna change or change an antenna matching. Hence, using such a method results in a limitation in tuning the antenna in accordance with various frequency bands.
Furthermore, in order to reduce a thickness of an external housing, metal is frequently used for a front case or a battery cover of a mobile terminal. In such a case, if metal is close to an antenna, the radiation performance of the antenna may be degraded. In order to mitigate such performance degradation, a certain distance between the metal and the radiation device of an antenna may be maintained, but maintaining the certain distance introduce a limitation in reducing a thickness of a mobile terminal, thereby lowering the product value. Additionally, it is possible that metal is not used around the radiation device of an antenna, but in such a case, a shape of the housing may be damaged by a double ejection structure that connects the metal structure with the plastic structure, and thereby the stability of the mobile terminal may decrease.
Furthermore, in order to mitigate the degraded radiation performance of an antenna due to the metal used in forming the external housing, it is possible to strengthen a ground connection by connecting a ground with the front case or battery cover made of metal. However, such a method entails an optimization method for the contact point of the ground when a mobile terminal is being developed because the antenna performance varies according to the type of the mobile terminal and the position of the contact point between the ground and the metal.